AT503728A1 - ROBOTIC - Google Patents

Description

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Ferrara

description

The invention relates to a flexible robot arm.

Oie DE 3630622 C2 (Bridgestone) shows an arm pivotable about exactly one axis for an industrial robot. The arm is attached to a rotatably mounted pulley, which is spanned by a rope, wherein at both of the pulley wegfQhrenden ends each having a so-called air muscle is arranged. An air muscle consists of a hose-like middle part and two plate-like end pieces, at least one of which is provided with an air passage. When the hose-like middle part blown up, it widens in the circumference and shortens in its length. This shortening of the length can be done by overcoming an external tensile force. If, in the application according to DE 3630822 an air muscle attracts, the Ami is pivoted in one direction of rotation; When this air muscle is released and the second air muscle attracts, the arm is pivoted in the opposite direction. The arm is "tactile" in the sense that it gives in with the application of an external force on its own elastic with a soft characteristic, which can be deduced with the help of position sensors and the consideration of the applied pressure in the air muscles on the greetings of the external force , The proposed arm for industrial robots has not prevailed. Since the elastic yielding occurs here in an uncontrolled manner, stiffer drive principles have been preferred, for example, by means of electric motors or hydraulic cylinders, and, if necessary, a soft grip is realized by separate gripping parts

US 4,964,568 shows a robotic arm driven by means of a plurality of hydraulic cylinders which can be pivoted relative to one another and is fastened to the side frame frame of a bed frame projecting above the lying surface of the bed. and presses on the back of a person lying on the bed on his stomach. The robot arm is controllable by the person lying on the bed by means of a control unit. Massage robots of this type have several disadvantages. Hydraulic systems are expensive, heavy, often spread a smell of hydraulic oil and carry the risk of contamination from leaking hydraulic oil with it. As a massage robots, they are also dangerous because a fault in the hydraulic system can act very quickly, very dangerous large forces on the treated people.

DE 195 24 666 C1 shows a massage robot, which is also arranged laterally on the bed. The upper linear actuators in three spatial coordinates movable tool holder can hold different massage means, and thus act on the massaging human. There are various programs for the control. The influence of the on humans is KraftgeregetL For the drives pneumatic cylinders or electric motors are intended. In order to avoid errors in the

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To exclude Ferrara dangers to the person to be massaged predetermined breaking points are provided in the system, which break when exceeding permissible forces.

Massage robots in a very similar design also show the US 5063552, and the US 2001 / 0014781A1. With appropriate control, these massage robots can massage quite well. But they are very expensive to buy, take up a lot of space, and are threatening. In addition, due to the cascading of each other unearfohningen in relation to some forces, as they may occur when moving through people in connection with the massage, they are very susceptible to damage.

The inventor has set himself the goal of providing a robot arm which is applicable in a variety of private households. From the described prior art, this concretely means that a robot arm must be created which is cheaper, safer, more robust, smaller and smaller easier, above all, the robotic arm has to be actively and passively safer than previously known robot arm. That it must be prevented with greater certainty that the robot arm is damaged by high forces something or someone injured and it must be prevented with greater certainty that the robot arm itself can be damaged by shocks, vibrations or incorrect loads. In addition, the robot arm must be easy to use and replaceable for a larger number of different applications.

To solve the problem, a robot arm is proposed, which exhibits the following structural features:

The robot arm is formed from at least three linked pivoting levers

Each pivot lever has a constant length, and consists of a support, with the first end of a base is rigidly connected. and at the second end of which a pivotable part is arranged.

The base of the third pivot lever is rigidly connected to the pivotable part of the second pivot lever. The base of the second pivot lever is rigidly connected to the pivotable part of the first pivot lever.

At least in the case of the first and the third pivot lever, the pivotable part is pivotable relative to the base about two axes which are not parallel to one another. Between the base and pivotal part of a pivot lever air muscles are arranged, by means of which the respective pivot position can be actively set. On the pivotable part of the third pivot lever, a tool holder is arranged, on which various tools can be arranged.

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Advantageous details of the mechanical structure and advantageous properties to be provided of the control of the robot arm will be described with the aid of the drawing:

1 is a schematic diagram of an exemplary robot arm embodying the invention in side elevation. Individual details are shown in cross-sectional view. Fig. 2: shows a possible sequence of information processing in the adaptation of the actual position of the tool holder to be moved to a desired position. The individual fields contain intermediate results of the information processing. The arrowheaded lines mean the acquisition of data from sensors, or calculations.

The base 1.1 of the first pivot lever 1 carries the entire robot arm shown in FIG. It can stand directly on the floor of a room or via fixable castors. But it can also be attached to a frame on a wall, a machine or a piece of furniture. It can also be arranged on a platform which moves under control in space or is mechanically rotatable relative to another fixed base in the space about a vertical axis of the base 1.1 projects with her rigidly connected support 1.2 up and ends in the ball 1.2 .1 of a ball and socket joint. The pan of this ball-pan galena forms the pivoting part 1.4 of the first pivot lever 1. Between base 1.1 and pivoting part 1.4 three parallel to the support 1.2 aligned air muscles 1.3 are arranged their attachment points on the pivotal part 1.4 form the vertices of a triangle in the middle of the Ball 1.2.1 is arranged by shortening one or two air muscles 1.3. and by stretching the two other air muscles or the third air muscle, the pivotable part 1.4 is pivoted about the center of the ball 1.2.1 to all those axes which extend through the center of the ball 1.2.1 and are normal to the orientation of the air muscles. Since each of the possible pivoting movements of pivoting movements can be thought to be composed of exactly two axes, this means, in the usual way for robotic arms, that the pivotable part 1.4 is pivotable about two axes to rotational movement about a third axis, namely those which are parallel to the airmovements is the pivotable part 1.4 is prevented by a stop. This stop is formed by a rigidly pivotable part 1.4 1.4.1 pin, which projects into a groove on the surface of the ball 1.2.1 This groove on the surface of the ball 1.2.1 lies in such a plane of symmetry of the ball, which to The orientation of the air muscles 1.3 is parallel rotational movement about this third axis could not be sufficiently well controlled by the mutually parallel air muscles 1.3, and is therefore completely avoided by the described attack. The ball has a hole in the longitudinal axis as a cable gland.

In place of the ball-socket joint described could also be used on Kardangelenken-turned, being used at the location of a ball two circular cylindrical axle. A first axle pin is normally aligned for support. The second

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Ferrara

Axle is aligned normal to this and pivotally mounted about its axis. Oer pivotable part is pivotally mounted on the second pivot pin about its axis.

Upper intermediate pieces 1.4.2 and 2.1.1, the base 2.1 of the second pivot lever 2 is rigidly connected to the pivotable part 1.4 of the first pivot lever 1. The spacers 1.4.2 and 2.1.1 can be mounted together in several different positions, whereby the angular position between the pivotable part 1.4 of the first pivot lever 1 and the base 2.1 of the second rocker arm 2, and thus the optimal starting position of the two pivot levers for the respective Einsalzzweck is adjustable to each other.

In the example shown, the pivotable part is 2.4. of the second pivot lever 2 relative to the base 2.1 of this pivot lever only about an axis rotatable. The pivotable part 2.4 is therefore mounted on a support 2.2 of this pivot lever normally aligned, cylindrical axle bolt, and not as described above on a ball.

The third pivot lever 3 is constructed in the same way as the first pivot lever 1. Its pivotable part 3.4 is thus pivotable relative to its base 3.1 about two axes.

The base 3.1 of the third pivot lever is directly connected to the pivotable part 2.4 of the second pivot lever.

The pivotable part 3.4 of the third pivot lever is equipped with a tool end 4, preferably in the form of a lockable Steckvorvfchtung for various tools. Tools in this sense may be various electrically or pneumatically controllable gripper or rigid items such as Steckvomchtungen, hooks, Hebei creators, chisels, wrenches, etc. The grippers can in turn hold tools such as e.g. various massagers, cleaning cloths, normal hand tools, telephone handsets etc.

In adaptation to the expected torque loads pivot lever 1 should be designed to be stronger than pivot lever 2, and pivot lever 2 stronger than pivot lever 3. Thus, the pivot lever 1 is also the heaviest, and the pivot lever 3 of the lightest. This also brings against another weight distribution the advantage that higher acceleration of the tool end 4 are possible.

The described sequence "biaxial joint - lever of constant length - uniaxial joint - lever of constant length - biaxial joint" corresponds approximately exactly to the sequence "shoulder joint - upper arm - elbow joint - forearm - wrist * of the human arm. Therefore, the possibilities of movement of the so trained robotic arm by the people using it very quickly intuitively very well understood, and therefore optimally used without a long training period. Thus, the described concatenation of self-variable länbaren pivoting levers with intermediate two- or uniaxial joints

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Ferrara is an extremely good compromise between the variety of possibilities of movement of the tool end on the one hand, and low cost on the other hand.

Lufl muscles have the disadvantages over control elements such as fluid-operated cylinders or electric motors that they can exert targeted controllable force only in one direction, and that thus at about the same expense only a significantly poorer positioning accuracy can be achieved. Above all because of the second of these disadvantages, the advantages of the air muscle for robotic applications have not been seen enough, and therefore hardly used

Especially in applications for robotic arms, which serve the personal needs of people, and simple tasks to do, the easily achievable with air muscles positioning accuracy is quite sufficient. Work to be considered is, for example: carry massagers, hold telephone calls. guiding a vacuum cleaner, cleaning windows, painting, holding objects such as tool trays in a predetermined position, etc. In applications of this kind, the relatively poor positioning accuracy of air muscles is not at all a disadvantage.

The use of pneumatic muscles as a cleat for robotic arms offers a number of important benefits:

Soft stop

The fact that movement of the robot arm is caused by the air volume elastic medium, the force-displacement characteristic is soft elastic, and the action on an external object can not change abruptly from a small force to a large force.

Extreme robustness (paseive safety self-protection)

Compared to the popular industrial robots with electric motors and rigid gears, the soft-elastic air muscles can intercept and dampen impacts on the robot itself. This makes the arm, despite its lightweight construction, extremely robust against peak loads and vibrations. The air muscles themselves are also very robust compared to piston-cylinder steep elements because they have no avenues on which parts slide and seal against each other, and because they are virtually impossible to damage as a result of their re-xibilltät as a hose by abutting objects.

Force-controlled movement (active safety third-party protection)

By measuring the position of the individual pivoting levers and the pressure applied in the individual pneumatic muscles, it is possible, by observing the pressure-path diagrams of the individual pneumatic muscles and the prevailing leverage ratios, to recalculate a control unit which applies external force to the tool end 4. That The force applied to the outside can be fixed, without the need for extra force sensors. By the control can be specified, with which maximum force against an external resistance, the

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Ferrara may be pressed against the auszuschenden movement. This maximum force can be controlled relatively safely and well, since the deformation characteristic of the robot arm is a soft elastic *, and thus smaller imposed from the outside movement disorders do not lead to abrupt changes in the forces in the robot arm. By the way, it is also quite possible to let the robot arm follow this object on an object under pressure if this object moves within certain limits. Since the individual parts of the robot arm are light, they hardly pose a danger in a collision with humans.

By measuring the exerted muscle strength. e.g. By means of strain gauges in the line of action of the force, a further increase in accuracy is possible.

Safety (passive safety in the event of a fault)

Even without providing predetermined breaking points in the robot arm, it can be ensured that even with faulty control by the robot arm, no dangerously large forces are exerted on people located in its area, for example by limiting the pressure in the pneumatic muscles by means of pressure relief valves.

economical

Due to the simple structure of pneumatic muscles are cheaper than hydraulic or pneumatic cylinders, or comparable usable electric drives.

ease

Air muscles have a much lower weight than in the effect comparable actuators in common other construction.

The air muscles are normally attached directly to the base of the pivoting lever, or on the most direct connection path by tension-resistant tension members, such as a steel cable, a chain, or a pull rod. For the respective pivotable part of the respective pivot lever, the air muscles should be exclusively on direct way by tension members such as ropes, which are attached on the one hand to the air muscle, on the other hand to the base or on the pivotable part of a pivot lever. All other possible transmission mechanisms, such as pivoting levers, gears, pulleys, etc., not only mean additional acquisition costs, but are also usually sensitive to damage due to improper handling or little maintenance. Last but not least, parts of this type are also dangerous for people who come into contact with it and need safe covers - which in turn mean effort and can even be damaged.

Robustness and safety are also achieved by the combination of the pneumatic muscles with the described sequence of three pivoting levers, in that the robotic arm can yield against heavy load from almost any direction by rotating in the joints as intended, and by stretching the air muscles. With this construction, it is easily possible to build a Robotereim, which on the one hand can handle so sensitive that he is single grapes from a vine

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Ferrara can pick and pick, on the other hand can hold a steel object such as a chisel, which is hammered with a heavy hammer, without the robotic arm is damaged.

Because the individual pivot levers of the robot arm are not variable in length, the necessary lines for compressed air supply, sensor signals and electrical line for any power tools held at the end of the tool can be well secured to the base and pivoting parts. With a small length reserve between the individual joints they are only slightly pivoted when moving the robot arm, but not beyond linear movement. In a particularly elegant variant of the routing these are performed in the joints through holes in the ball joint or in hinge pin.

Of essential importance for the practical use of the robot arm are as with any robotic arm, the possibilities of control desirable, for the practical application by non-professional users important and on the proposed construction quite feasible construction methods are for example: Prepared Weg-Zert-force profiles.

; Teach-in i.e. A programming of a subsequently by the robot arm auszuführenden motion sequence by a single manual control of the arm movement, while recording this sequence of movements.

Teach-in by the fact that the robot arm in the appropriate mode at any place by the programmer is touched and moved manually in the desired, later automatically run through sequence.

Editability of programmed movements with respect to geometric changes, speed changes, changes in the forces to be applied.

Classification of safety-relevant limitations such as maximum speed, maximum acceleration, maximum forces.

Adjustable range of large-scale positional tolerance with constant contact force, as long as the arm is in contact with the target object. The arm follows the force-controlled object, even if the object moves within certain limits.

A regulation in that a set position of the robot arm is automatically restarted when the robot arm is moved from this position due to an external effect such as a blow to one of its moving parts.

Because the air muscles dampen vibrations that are applied from the outside, the robot arm can also be used well in or on devices that self-generate. For example, a robot arm according to the invention can also be used in a car.

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Ferrara

Especially for that teach-in, in which the robot arm is guided by hand and for the force control on contact, the vargehlagenen design of the robot arm is very advantageous because the robot arm is very light, movement is hardly opposed to friction and the soft-elastic kinematics greatly simplifies contour tracing.

The proposed combination of features of a robotic arm results in a hitherto unequaled bundle of advantages: cost-effectiveness, robustness, flexibility in terms of applications, safety, security and intuitive understanding of the possibilities of movement. For the first time, practically useful robot arms are made possible, which can be used economically for smaller and smaller commercial enterprises and with increasing sales figures even for private households.

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Claims (14)

, [me sn «a / as] 8Z: si aa 90, zo / ee ee ··· ···· ··················································································· 1. Robotic arm which is formed of at least three interlinked pivoting levers wherein each pivot lever has a constant length and at the end of the last pivot lever is provided a pivotable holder for tools characterized in that each of the three pivoting levers (1, 2, 3) consists of a base (1.1, 2.1, 3.1), a stub (1.2, 2.2, 3.2), a pivotable part (1.4, 2.4.3.4) and pneumatic muscles (1.3 , 2.3.3.3), wherein the base and pivotable part of a pivot lever are secured to opposite ends of the stub, the pivotable part is rotatably mounted about the axis about one or two axes, and wherein between the base and pivotal part of a pivot lever several air muscle on different sides of pivot axes of the pivotable part are arranged. 2. Robot arm according to claim 1, characterized in that the base (3.1) of the pivot lever (3) is rigidly fixed to the pivotable part (2.4) of the pivot lever (2), and that the base (2.1) of the pivot lever (2) rigid is attached to the pivotable part (1.4) of the pivot lever (1). 3. robot arm according to claim 1 or 2, characterized in that at joints at the ends of the pivot arms (1, 2, 3), first a joint with pivoting about two mutually normal axes, then a joint with pivoting about a single axis, and then again follow a joint with pivoting about two mutually normal axes. 4. robot arm according to one of claims 2 or 3, characterized in that the position of the base (2.1) of the second pivot lever (2) on the pivotable part (1.4) of the first pivot lever (1) can be mounted in different orientations. 5. Robot arm according to one of the preceding claims, characterized in that the pivot lever 1 is made stronger than pivot lever 2, and pivot lever 2 stronger than pivot lever. 3 6. robot arm according to one of the preceding claims, characterized in that all the air muscles of the individual pivoting lever with the associated pivoting parts exclusively upper directly wvkende tension members such as ropes. Belt. Chains. Tie rods, etc., which are attached on the one hand to the air muscle, on the other hand, on the pivotable part, are in mechanical operative connection. 7. robot arm according to one of the preceding claims, characterized in that the pressure in the air muscles is limited by a pressure relief valve. 8. Robot arm according to one of the preceding claims, characterized by. the control measures the position of the individual pivoting levers and the pressure applied in the individual muscles of the air, and see page 9 ζτ® vavwiaasNi * Ί «πα ΤβΟΟΖ SZZiO C7 + XVd ts: st 900Ζ / Ζ0 / ΪΖ UCI8 SN KH / HSl 8Z : ST Hd 90. • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 9 · 9 · 9 · 9 · 9 · 9 · 9 9 · ·· 9 Ferrara relationship of the pressure-stroke diagrams of the individual air muscles and the geometric lever ratios is calculated back to the force acting at the end of the creator. 9. robotic arm according to one of claims 1 to 7, characterized in that the force applied by individual air muscles force is measured more directly than according to claim 8, for example by means of strain gauges. 10. robotic arm according to claim 8 or 9, characterized in that the force exerted by the tool end force monitored by the controller and kept constant or limited. 11. Robot arm according to one of the preceding claims, characterized in that required lines are guided at joints on the rotor arm through holes in the joint ball or in the joint bolt. 12. Robot arm according to one of the preceding claims, characterized in that a joint is designed for a biaxial pivoting movement as a ball-socket joint, wherein a groove in the surface of the ball (1.2.1) extends, in which a rigid with the pan connected bolt (1.4.1) protrudes wherein the groove lies in such a plane of symmetry of the ball which is parallel to the orientation of those air muscles (1.3) which engage the pan. 13. Robot arm according to one of the preceding claims, characterized in that the controller is switchable into a mode in which they aufepich movements of the robot arm, which are caused by the robot arm is taken at any position and moved by external forces, aufeeichnet. 14. Robot arm according to one of claims 8 or 9, characterized in that it repeats recorded processes as far as it is possible in compliance with predetermined, automatically monitored by the robot arm itself force limits. Page 10 vavtwai SNi iaia T600Z 9ZZL0 XVd frS: ST 900Z / Z0 / VZ